Serum hyaluronic acid in polymyositis: high serum levels tend to correlate with disease activity.

OBJECTIVE Polymyositis (PM) is a rare systemic idiopathic inflammatory myopathy. Hyaluronic acid (HA) is closely linked to inflammatory cellular reactions and disease activity. Increased serum levels of HA have been reported in several inflammatory diseases, but currently, there are no studies analysing the HA in PM. Thus, clinical association of HA with PM in patients was determined in the present study. METHODS The present cross-sectional study was performed at one centre from 2012 to 2013 and included 35 consecutive adult patients with PM (Bohan and Peter criteria, 1975) and 38 adult healthy volunteers. The serum HA was assessed with anti-HA antibody, using the specific ELISA/EIA kits according to the manufacturer's protocol. RESULTS The average age, distribution of females and ethnicity were comparable in patients with PM and the control group. Regarding disease status, patients with PM had a median patient visual analogue score (VAS) of 2 [0-6], physician VAS of 1 [0-3], MMT-8 of 74 [68-80] and HAQ of 0.48 [0.00-1.14]. The serum levels of HA were also significantly increased in patients with PM (390±412 ng/mL) compared to healthy subjects (129±119 ng/mL), p=0.001. In an additional analysis, the serum levels of HA did not correlate with PM demographic data (gender and ethnicity), current organ involvement or autoantibodies and were not been influenced by the use of prednisolone and/or immunosuppressives by the PM patients. However, there was a positive correlation between serum levels of HA and VAS (patient and physician), and a negative correlation between serum levels of HA and MMT-8. CONCLUSION High serum levels of HA were observed in patients with PM and tended to correlate with PM disease activity. Additional studies are needed to assess this correlation, as well as to understand the mechanism involved in the pathogenesis of PM by HA.